Ladder-type cable tray is used by industry to support electrical cable. A length or section of ladder cable tray comprises a pair of side rails connected by cable-supporting rungs extending between the rails at intervals along the tray. Cable tray sections are spliced together using splice plates to form a cable tray run. Splicing cable tray sections using expansion splice plates is required when installing the cable tray run outdoors where temperature variations may cause thermal expansion and contraction of the cable tray sections.
FIG. 1 illustrates a conventional expansion splice plate for fiberglass cable tray. The splice plate, made of fiberglass, is generally L-shaped and is configured to be secured to adjoining sides (rails) of adjacent cable tray sections between upper and lower flanges of the rails. The conventional expansion splice plate includes a first set of openings for receiving fasteners to secure the splice plate to a rail of one of the adjacent cable tray sections. A second set of openings includes slot-shaped openings for receiving fasteners to secure the splice plate to a rail of the other of the adjacent cable tray sections. The slot-shaped openings allow for longitudinal movement of the tray sections relative to one another. A conventional expansion splice plate for metal cable tray (not shown) comprises a flat metal plate with slot-shaped fastener openings that permit longitudinal movement of the tray sections relative to one another.
Typically, supports, such as trapeze supports, are installed at every quarter span of the cable tray run, as illustrated in FIG. 2. However, when using the above-described conventional expansion splice plate, a support must be installed at each end of the adjacent tray sections to adequately support the splice. Thus, two supports must be installed for each tray section in addition to the support at each quarter span, making the installation process more time-consuming and expensive. Alternatively, elimination of one or more quarter-span supports will result in greater deflection of the cable tray run, which is undesirable.